Thermographic reproduction apparatus with thermosensitive heat regulator



H. J. THOMISZER 3,202,818 THERMOGRAPHIC REPRODUCTION APPARATUS WITH THERMOSENSITIVE HEAT REGULATOR Filed June 7, 1962 46 2 1 FIG. 3

Aug. 24, 1965 I I) I R m mw wl T M E 3 L s w M 5 m M 6 Y G O 11M I l 6 F Y o I 2 3 I I i w 2 6 7 w T m s J 3 T a a R a m I Q Y 6 m 3 85 N 5 6 5 5 5 n I. u: |9!l u T 3 4 all I G J W? F T w United States Patent s,2a2,srs THERMOGRAPHIC REPRGDUfiTION APPARATUS WITH THERMGSENSiTlVE HEAT REGULATOR Hubert J. Thomiszer, Siroirie, IlL, assiguor to Eugene Dietzgen (30., Chicago, Ill., a corporation of Deiaware Filed June 7, 1962, Ser. No. 230,731 5 Claims. (Cl. 250-65) The present invention relates in general to the art of copying graphic material, such as typewritten and other written or printed material, sketches, tracings, drawings, photographs and the like, and has more particular reference to the production of thermographic copies of original material to be reproduced, the invention in its more specific aspects pertaining to temperature responsive control means for regulating a heater.

The production of copies of original graphic material, on thermosensitive copying material, may be accomplished by exposing the material to the action of heat which, in the interests of uniformity in the resulting copy or print should be held at a constant level, so that all prints may be processed at the same temperature, and each component area of the copying material subjected to the same quanta of heat as every other area of the sheet during treatment, the maintenance of isothermic treating conditions during the processing of heat sensi tive copying material for the production of copy prints being especially important in processing equipment adapted for continuous print production by carrying the heat sensitive material progressively through a heated zone.

An important object of the present invention is to provide improved heat responsive means for controlling, within close limits, the operating temperature of heating apparatus; a further object being to provide an appropriately located thermistor in heat exchange relationship with thermosensitive copying material while the same is being processed by the application of heat thereto, in order to accurately control the temperature at which the material is treated.

Anotherimportant object of the present invention is to provide an electrically energized component for processing heat sensitive copying material, and to employ a thermosensitive element maintained continuously in heat exchange relationship with the copying material being treated, the heat sensitive element being connected to control the electrically energized component in accordance with the prevailing temperature at which heat is applied upon the sheet being treated; a further object being to employ an electrically energized lamp as a source means for controlling the application of heat upon thermosensitive copying material, and to employ a thermistor as a'heat responsive element maintained in thermal contact with the material being processed, the thermistor being controllingly connected with electrical circuitry forming translation means connected to control the delivery of energizing power to the lamp.

Another important object is to provide heating apparatus embodying a pair of conveyor elements, such as a drum member and a drum embracing belt member, including means for heating at least one of said members, at least one of said members being movable to transport a sheet of heat sensitive material in contact with the heated member from an inlet to a delivery station, including a heat sensing element, such as a thermistor mounted on one of the members, in position to be supported in heat exchange relationship with respect to thermographic copying material as it travels between the inlet and discharge stations, and including means controlled by said heat sensing element for regulating the amount of heat applied to the material as it passes between said 2 stations; a further object being to embed the heat sensing element in one of the conveyor elements in position extending adjacent the material being treated.

Another important object of the present invention is to provide improved apparatus for applying heat to a sheet of material substantially uniformly in all portions of the sheet; a further object being to provide improved means for heating a sheet of sensitive copying material, in order to produce therein a facsimile of graphic material contained in a master or original.

Another important object of the invention is to provide improved means for heating a sensitive copying sheet at a temperature suflicient to develop a highly visible and stable image in the sheet; a further object being to provide a heating oven through which the sheet may be delivered rapidly and at a uniform rate of speed, thereby to heat the sheet progressively throughout its entire length at a rapid uniform rate of speed, to the end that sheets of relatively large area may be uniformly heated in apparatus of relatively small size; a still further object being to utilize a heating roller of relatively small diametral size of the order of three inches or less, for sheet heating purposes; a further object being to form the heating roller as a cylindrical sleeve of metal, such as aluminum, in conjunction with means for continuously rotating the sleeve While passing the sheet to be treated around and in surface contact therewith, the heater being mounted within the sleeve in order to heat the same to a desired temperature; yet a further object of the invention being to form the sleeve as a metal tube having a black coating upon the inner surface thereof and an outer coating of any desired color other than black; still another important object being to utilize an elongated tubular infrared ray lamp as a means for heating the sleeve, said lamp being preferably mounted in stationary position coaxially within the rotatable sleeve of the sheet treating apparatus.

Another important object is to provide a sheet traveling belt suitably mounted upon supporting rollers and forming a bight embracing a heating roller, whereby to retain a sheet of sensitive copying material upon the roller while traveling the sheet between sheet receiving and sheet delivery stations spaced apart circumferentially of the roller; a further object being to employ a traveling endless belt of woven fiberglass fabric material impregnated with Teflon plastic, which comprises a tetrafluoroethylene polymer; a still futher object being to employ an endless belt having a bight embracing the heating roller and subtending an angle of the order of 230 between a sheet receiving and a sheet delivery station de fined by a pair of said rollers, a third roller being mounted in shiftable, resiliently suspended bearings for maintaininga desired tension in the belt.

Another important object is to provide a heat insulating jacket around the heating roller and its associated traveling belt, including the belt supporting rollers, in order to constitute the apparatus as a heating oven; 3. further object being to utilize fiberglass insulation having thickness of the order of one-half inch as insulating means enclosing the heating roller and its associated traveling belt, the insulation being formed with openings permitting sensitive sheet material to be delivered. between the belt and the heating roller at the sheet receiving station and to permit developed sheet material to be delivered from between the belt and heating roller at the sheet delivery station.

Another important object of the invention is to provide improved thermostatic means for continuously determining the temperature at which developing heat is applied to a sheet being treated as it travels around the heating cylinder, of the oven, between sheet receiving and delivery stations; a further object being to employ become apparent as the same is more'fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention. I Referring to the drawings:

FIG. 1 is a front elevation of one side portion of apparatus embodying the present invention;

FIG. 2 is a sectional view taken substantially along the line 2-2 in FIG. 1; i

FIG. 3 is asectional view taken substantially along the line 3-4: in 'FIG. 2 and showing the end portions of the apparatus remote. from the end portions shown in FIG. 1;

FIG. 4 is an enlarged sectional View taken substantially along the line i4- in FIG. 2; and 7 FIG. is a diagram of electrical circuitry.

To illustrate the invention the drawings show transport apparatus 11 for conveying sheet material 12 along a selected path between sheet receiving and sheet delivery stations 13 and 14. The sensitive sheet material may comprise a web, as of paper or other suitable sheeting, containing a sensitive composition that is convertible to highly visible, stable and inert condition upon exposure to heat. The'sensitive coating may comprise any suitable substance'having the foregoing characteristics, as, for example, the material described in the copending application ,of Klimkowski, Beauchamp and Bauer for United States Letters Patent on diazotype reproduction material, filed February 1, 1960, Serial No. 5,688. Such material comprises a diazo compound and an azo dye coupling component, together with a substance, capable of producing or permitting a diazo. developing reaction when heated at temperatures of the order of, say, 300

Fahrenheit. Such diazotype material is not only heat sensitive, but is convertible to stable, inert and colorless condition upon exposure to radiation containing ultra violet rays either alone or in combination with other radiation, including visible light.

In making a copy of an original or master having imprinted or otherwise applied thereon graphic markings or characters embodying material capable 'of absorbing ultra violet radiation, a sensitized copy sheet may be stacked with the original or master to be reproduced, in order to form an exposure sandwich adapted for exposure of the sensitive material to ultra violet rays applied thereto through the original or master to be copied.

Latent images corresponding with the graphic markings or characters of the original, may thus be produced in the sensitive material, as a result of the diazo destroy- 7 ing or inactivating action of the radiation on all portions of the sensitive sheet, except such as are screened by the characters or graphic markings of the original during the exposure interval. The latent images thus formed in the copying sheet may then be stabilized and converted to permanently visible condition byheating the copying sheet at a temperature of the order of 300 Fahrenheit. i

The sheet transporting apparatus 11 preferably comprises a pair of cooperating sheet guiding and moving components 15 and 16, means being provided for heating at least one of the components in order to apply heat to a sheet of material as the same is transported by and between the components. To this end, a heater 17 may be provided for heating the component 15, which may be formed as a continuously turnablecylindrical sleeve 18 ofaluminum or other suitable heat conducting material. The component 16 may comprise an endless web of material forming a belt 19 having a bight 29 in embracing contact with the outer surfaces of the sleeve 18, the sleeve engaging portions of the bight 2t subtending an angle of the order of 230 at the axis of the sleeve. The belt 19 may be guided on rollers 21 and 22 disposed respectively at or adjacent the sheet receiving and tie livery stations 13 and 14. After passing around the guide roller 21, the belt may travel thence around and in contact with the peripheral surface of the sleeve 18, between the roller 21., at the sheet receiving station 13, and the" roller 22 at the sheet delivery station 14. From the roller 22, the endless belt 19 may be returned to the guide roller 21 after passing around an idler roller 23, which may be journalled in bearings resiliently suspended as on spring means 24, in order to maintain the endless belt 19 under desired resilient tension.

The sleeve member It; may be provided with a black coating upon its inner surface to constitute the same as a black body capable of absorbing heat readily from the source 17, the outer surfaces of the sleeve having any preferred coloration, other than black, in order to promote heat emission outwardly of the sleeve and into any sheet material held upon its outer surface, as the same is turned.

The belt 19 may comprise any suitable heat resisting web material, but the same preferably comprises fiberglass fabric impregnated with a tetrailuoroethylene polymer, such as is produced by E. I. du Pont de Nemours and Company under the brand name of Teflon, or similar chemically inert, synthetic plastic material'providing a heat resistant web of adequate strength. Since the surface of a woven fiberglass fabric sheet is not entirely smooth even When impregnated with Teflon brand plastic, it is desirable to provide the belt with a lining or surface layer 25 of pure Teflon brand plastic, or like plastic material upon the surface of the belt which faces inwardly upon the sleeve 18. Teflon brand plastic is a good heat reservoir because of its low thermal conductivity. Accordingly, it is well adapted for use in apparatus for transporting sheetmaterial while exposing the same to the action of heat.

As shown, the apparatus may comprise a stationary support structure embodying a pair of spaced apart end plates 26 of heat resistant material such as Bakelite or Formica, with glass or asbestos as a filler, said end plates being mounted on a suitable support base 27, in any suitable, preferred or convenient fashion. The end plates 26 may be provided with suitable journals for supporting axles extending at the opposite ends of the rollers 21, 22 and 23. An axle at an end of one of said rollers, such as the roller 22, may be drivingly connected with a sprocket 27. Suitable motive means may be provided for driving the sleeve 18 and the belt 19. Such motive means may conveniently comprise an electrical motor 29 which may be mounted upon the base 27 of the frame. The motor, through a shaft connected worm, may drive a countershaft journalled in the frame plates 26, at relatively slow speed, by means of a worm wheel 32 on the countershaft. The countershaft may carry a driving sprocket 33 which may be drivingly connected with the sprocket 28, as by means of a chain 34. Any other suitable or preferred driving mechanism may, of course, be employed to connect the motor 29 for driving the sleeve 18 and belt 19.

In alignment with the axis of the sleeve 18, the end plates 26 may be formed with perforations 35 sized to permit the insertion therethrough of the heater 17, which preferably comprises an elongated tubular infra-red ray lamp 36 of conventional construction, the same conveniently comprising. a tubular quartz lamp of the sort identified as No. T.?, manufactured by General Electric Company, which has a color temperature of 2400 K. The opposite ends of the infra-red ray lamp may extend outwardly of the plates 21, such outwardly extending lamp ends carrying electrodes 36' fitted thereon in position for reception in connection clips 37, which may be supported on the walls 26 and provided with means for electrically connecting the same in external lamp energizing circuitry 38 of the sort shown in FIG. 5.

While and so long as the lamp 36 is appropriately energized for operation as an infra-red ray emitter, the resulting radiation will be applied upon the inner black coated surface of the sleeve 18, which will absorb substantially all of the radiation emitted by the lamp. Such absorbed radiation will result in heating the sleeve 18 to the temperature required for the development of the sensitive sheet 12.

Suitable motor control means of conventional character, may, of course, be provided for starting and stopping the motor and for regulating its speed in order to determine the rate of travel of sheet material 12 on the sleeve 18 between the receiving and delivery stations 13 and 14. An important aspect of the present invention resides in the provision of heat treating equipment of the character described, in which the sleeve 18 is minimal size, the same preferably having a diameter of the order of 3 inches or less, whereby the entire apparatus-is unusually compact, it being possible to provide a serviceable heater embodying a sleeve of diameter as small as 1 inch.

In order to hold the sleeve 18 within the belt bight 20, positioning roller means 39 comprising a plurality of spaced apart roller sections 39' on a supporting spindle or stem 40 may be suitably mounted in bearings on the end plates 26 in position to rollingly bear upon the bight remote portions of the sleeve 18 between the guide rollers- 21 and 22. The positioning roller means may be enclosed within a shell or housing 41 comprising a bent piece of sheet metal secured at its opposite ends on the end plates 26, the opposite sides of said cover may be formed with flat portions 42 and 43 extending at the sheet receiving and sheet delivery stations in order to aid in guiding the sheet as it is received between the sleeve 18 and the belt at the receiving station 13 and as it is released from between the sleeve and belt at the delivery station.

A sheet receiving and guiding shelf 44 may be secured at its opposite ends to the end plates 26 in position extending therebetween in position defining a narrow sheet guiding slot with the fiat side 42 of the cover 41, said flat side and said shelf extending tangentially with respect to the roller 21 and the sleeve 18, at the sheet receiving station 13.

The cover 41, adjacent its flat side 43, at the sheet delivery station 14, may carry a blade 45 defining one side of the delivery station 14, said blade having an edge adapted to ride upon the surface of the sleeve 18 in order to separate sheet material from the sleeve and guide it onto the flat side 43 of the cover 41 at the delivery station, in order to eject the treated sheet from the developing apparatus.

In order to minimize heat loss from the sleeve 18 and belt 19, the same may be enclosed and housed within a heat insulating casing which may conveniently comprise a sheet of fiberglass insulation 46 having thickness of the order of one-half inch, said layer-extending between and being secured at its opposite side edges upon the end plates 26 in any suitable or convenient fashion, with the medial portions of the layer embracing the roller 23, the guide rollers 21 and 22 and the stretches of the belt 19 between said rollers, the opposite ends of the insulating layer curvingly embracing the guide rollers 21 and 22 and terminating at the sheet receiving and delivery stations 13 and 14.

An important feature of the present invention resides in the provision of heat sensitive means 47 responsive to the temperature at which heat is applied to the copying sheet 12 by the sleeve 18 and operable to control the heating lamp 23 to maintain the operating temperature at which heat is applied to the sensitive sheet material within close limits.

The heat sensitive means 47 preferably comprises a small lump or pellet of material forming a thermistor 48 preferably configurated as a spherical body having a flat surface 49 formed on one side. The thermistor is preferably mounted in an opening 50 formed through a fiberglass fabric strap 51, with the flat surface 4-9 of the thermistor in facing engagement with a thin layer 52 of pure Teflon or like plastic secured on the front surface of the strap 51 in position overlying the opening, so that the fiat face of the thermistor is exposed through the thin layer 52 to the heat in the sleeve 18 at the precise temperature applied to a sheet of sensitive material 12 as the same is carried around the sleeve and between it and the belt 19, from the sheet receiving station 13 to the sheet delivery station 14.

As shown, the diametral dimension of the thermistor element 48 is greater than the thickness of the fiberglass fabric strap 51 so that a substantial portion of the thermistor element projects outwardly of the back side of the strap. To heat insulate such projecting portions of the thermistor from circumambient atmosphere, it may be enclosed and covered on the strap as by means of a cover patch 53 of any suitable, preferred or convenient insulating material, such as a piece of Teflon impregnated fiberglass fabric similar to the material of the strap 51, silicon cement being preferably employed to adhere the cover patch to the strap, around the thermistor pellet, the central portions of the cover patch being also cemented to the surfaces of the thermistor covered thereby; and silicon cement being applied within the cover patch to secure the thermistor to the material of the strap peripherally of the opening 50. If desired, the outwardly facing surfaces of the cover patch may be provided witha facing layer of plastic material such as Teflon; and conductors 54 electrically connected with the thermistor may extend outwardly thereof through the cover patch 53, in order to electrically connect the element in the circuitry 38 for controlling the delivery of operating energy to the lamp 36.

The thermistor carrying strap may be mounted on a holder 55 comprising a curved strip of sheet metal having end flanges 56 upon which the opposite ends of the strap may be secured, as by means of epoxy resin cement. The strap holder in turn may be supported, within the cover 41, by means of a bracket 58 formed integrally on or secured to the cover, as by fastening screws, riveting or spot welding, and carrying the holder 55, as by means of fastening screws or rivets 57. The bracket may thus be supported in position pressing the thermistor carrying strap 51 resiliently and wipingly upon the surface of the sleeve 18, between a pair of adjacent sections 39 of the positioning roller means. The thermistor, thus, is supported in heat exchange relation with the sleeve immediately before it engages with the sheet to be heated at the sheet receiving station 13. As a consequence, the thermistor is disposed in position to accurately measure variations in the temperature at which heat is applied to the material 12, and hence to correspondingly regulate the heat producing lamp 36.

As shown more particularly in FIG. 5 of the drawings, the heater element 36 may be energized from any suitable, preferred or convenient electrical power source 59 through an energizing circuit including supply conductors 60, disconnect switch means 61 and a relay switch 62 operable under the control of a solenoid 63 to selectively permit and prevent the delivery of operat ing energy to the heating element 36. Conventional amplifying means 64 may be provided for selectively actuating the solenoid 63 of the relay switch under the control of the heat responsive thermistor 48, said amplifying means 64 conveniently comprising a device of the sort manufactured by Fenwal Inc. as its Model No. 535

temperature controller, such amplifier being energized by electrical power supplied from the source 59 through the disconnect switch means ell-and having the thermistor 48 controllingly connected therewith, as by means of the leads 54. The actuating solenoid 63 of the relay switch 62 may also be energized from the power source & under the control ofthe amplifier 64 as indicated by the connection of the solenoid 63 in series with the out put side ofthe amplifier across the conductors 6t); and the operating characteristics of the amplifier 64 may be varied by adjusting ganged potentiometers 65 electrically connected therewith, in order to cause the switch 62. to open and close at any desired temperature level, within the operating range of the amplifier apparatus, as determined by the thermistor.

The control apparatus of the present invention makes it possible to maintain, precisely and accurately, a desired temperature level of heat applied for the processing of sensitive material as his carried between the inlet and delivery stations 13 and 14. Apparatus of the sort erein disclosed permits the temperature level to be controlled within 21 5 range above and below a precise desired temperature level and furthermore provides an extremely rapid response when coupled with an infra-red lamp as a heat source within a thin walled metal heating cylinder. The foregoing thermistor arrangement also assures minimal thermal lag from the moment the thermistor signals for an increase or a decrease in heat required for optimum development. Since the time constant for the thermistor mounted in place in the manner disclosed is approximately one-tenth (0.1) of a second, it is desirable that the time constant for the mechanical heat transfer system consisting of infra-red lamp and aluminum cylinder be of the same order of magnitude. Such a time constant was attained by employment of an infrared ray source 47 of the character described, in conjunction with a sleeve 19 comprising a thin walled aluminum cylinder having thickness of the order of 35 onethousandths (0.035) of an inch. The time constant of the ray source is approximately one-twelfth (0.083) of a second, and the time constant for the aluminum cylinder is approximately the same value. 'As a consequence, the total time constant for the transfer of heat from the ray source to the sheet material being treated is of the order of one-quarter (0.25) of a second. This circumstance coupled with the small time constant of a thermistor mounted in the manner described has permitted the use of a cylinder having the diameter of the order of 3 inches while providing for proper development of the sensitive material at acceptable linear speeds of the order of 7 to feet per minute.

The use of infra-red radiation together with the thin wall aluminum cylinder of small diameter in conjunction with a thermistor having an extremely small time re-' sponse constant, because of the manner of mounting it, has permitted accurate temperature control on a practical basis thereby making possible the heat'devel'opment of diazotype sensitive material as a continuous operation in apparatus that is sufficiently compact to allow for its convenient use as a piece of table-top omce equipment.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed'as follows:

1. Apparatus for the development of a ray sensitive sheet containing heat activatable developing material, comprising a pair of cooperating sheet transporting members, including a turntable sleeve and a belt having a sleeve embracing hight, operable to carry a sheet to be developed from a sheet receiving to a sheet delivery station, heating means operable to heat one of said transporting members toconstitute the same as means to heat a sheetas it is carried, by and between the sleeve and the sleeve embracing bight of the belt, from the receiving to the delivery station, heat sensing means mounted wipingly in heat exchanging relation with respect to a said sheet transporting member forming a body movable relative to the sensing means, and means controlled by said sensing means for regulating the sheet heating means, said sensing means comprising a fiberglass mounting strap impregnated with a tetrafiuoroethylene polymer and formed with a facing layer of clear plastic having a smooth body engaging surface adapted for wiping engagement with said body, said strap being formed with a pocket behind said facing layer, a thermistor formed with a flat face, silicon cement securing said thermistor in said pocket in position with its flat face in surface contact with the back of said facing layer, and a resilient sheet metal bracket providing spaced anchoring abutments, said strapbeing secured on said abutments on opposite sides of said thermistor, to support the same in position to press said body engaging surface upon said body and thereby mount the thermistor in heat exchange relation with the body, through said facing layer. g

2. Apparatus for the development of a ray sensitive sheet containing heat activatable developing material, comprising a pair of cooperating sheet transporting members, including a turnable sleeve and a belt having a sleeve embracing b ight, operable to carry a sheet to be developed from a sheet receiving to a sheet delivery station, heating means operable to heat one of said transporting members to constitute the same as means to heat a sheetas it is carried, by and between the sleeve and the sleeve embracing bight of the belt, from the receiving to the delivery station, heat sensing means mounted wipingly in heat exchanging relation with respect to sensing means, and means controlled by said turnable sleeve for regulating the sheet heating means, said sensing means comprising a fiberglass mounting strap embodying a facing layerhaving a body engaging surface adapted for wiping engagement with said turnable sleeve, said strap being formed with a pocket behind said facing layer, a heat sensitive element having a flat face secured on said strap in position with its fiat face in surface contact with the back of said facing layer, and mounting means providing spaced anchoring abutments said strap being secured on said abutments on opposite sides of said heat sensitive element, to support the same in position to press said body engaging surface upon said body and thereby'mount the heat sensitive element in heat exchange relation with the turnable sleeve, through said facing layer.

3. Apparatus for the development of a ray sensitive sheet containing heat activatable developing material, comprising a pair of cooperating sheet transporting members, including a turnable sleeve and a belt having a sleeve embracing bight, operable to carrya sheet to be developed from a sheet receiving to a sheet delivery station, heating means operable to heat one of said transporting members to constitute the same as means to heat a sheet as it is carried, by and between the sleeve and the sleeve embracing bight of the belt,rfrom the receiving to the delivery station, heat sensing means mounted wipingly in heat exchanging relation with respect to a said sheet transporting member forming a body movable relative to the sensing means, and means controlled by said sensing means for regulating the sheet heating means, said sensing means comprising a mounting strap havinga surface layer adapted for wiping engagement with saidbody, a heat sensitive element secured on said strap, behind said surface layer, and mounting means providing spaced anchoring abutments, said strap being secured on said abutments on opposite sides of said heat sensitive element, to support the same in position to press said surface layer upon said body to thereby mount the heat sensitive element in heat exchange relation with the body, through said layer.

4. Apparatus as set forth in claim 3, wherein the heat sensitive element comprises a thermistor.

5. Apparatus for the development of a ray sensitive sheet containing heat activatable developing material, comprising a pair of cooperating sheet transporting members, including a turnable sleeve and a belt having a sleeve embracing bight, operable to carry a sheet to be developed from a sheet receiving to a sheet delivery station, heating means operable to heat one of said transporting members to constitute the same as means to heat a sheet as it is carried, by and between the sleeve and the sleeve embracing bight of the belt, from the receiving to the delivery station, heat sensing means mounted Wipingly in heat exchanging relation With respect to a said sheet transporting member forming a body movable References (Iited by the Examiner UNITED STATES PATENTS 1,907,540 5/33 Hebler 73-351 2,927,210 3/60 OMara 250-65 2,937,354 5/60 Mazzarella 33 8-22 2,947,171 8/60 Peltola 73-351 2,958,778 11/60 Miller 250-65 2,977,558 3/61 Hampton 338-22 3,012,141 12/61 Thomiszer 250-65 RALPH G. NILSON, Primary Examiner.

20 ARCHIE R. BORCHELT, Examiner. 

1. APPARATUS FOR THE DEVELOPMENT OF A RAY SENSITIVE SHEET CONTAINING HEAT ACTIVATABLE DEVELOPING MATERIAL, COMPRISING A PAIR OF COOPERATING SHEET TRANSPORTING MEMBERS, INCLUDING A TURNTABLE SLEEVE AND A BELT HAVING A SLEEVE EMBRACING BIGHT, OPERABLE TO CARRY A SHEET TO BE DEVELOPED FROM A SHEET RECEIVING TO A SHEET DELIVERING STATION, HEATING MEANS OPERABLE TO HEAT ONE OF SAID TRANSPORTING MEMBERS TO CONSTITUTE THE SAME AS MEANS TO HEAT A SHEET AS IT IS CARRIED, BY AND BETWEEN THE SLEEVE AND THE SLEEVE EMBRACING BIGHT OF THE BELT, FROM THE RECEIVING TO THE DELIVERY STATION, HEAT SENSING MEANS MOUNTED WIPINGLY IN HEAT EXCHANGING RELATION WITH RESPECT TO A SAID SHEET TRANSPORTING MEMBER FORMING A BODY MOVABLE RELATIVE TO THE SENSING MEANS, AND MEANS CONTROLLED BY SAID MEANS FOR REGULATING THE SHEET HEATING MEANS, SAID SENSING MEANS COMPRISING A FIBREGLASS MOUNTING STRAP IMPREGNATED WITH A TETRAFLUORETHYLENE POLYMER AND FORMED WITH A FACING LAYER OF CLEAR PLASTIC HAVING A SMOOTH BODY ENGAGING SURFACE ADAPTED FOR WIPING ENGAGEMENT WITH SAID BODY, SAID STRAP BEING FORMED WITH A POCKET BEHIND SAID FACING LAYER, A THERMISTOR FORMED WITH A FLAT FACE, SILICON CEMENT SECURING SAID THERMISTOR IN SAID POCKET IN POSITION WITH ITS FLAT FACE IN SURFACE CONTACT WITH THE BACK OF SAID FACING LAYER, AND A RESILIENT SHEET METAL BRACKET PROVIDING SPACED ANCHORING ABUTMENTS, SAID STRAP BEING SECURED ON SAID ABUTMENTS ON OPPOSITE SIDES OF SAID THERMISTOR, TO SUPPORT THE SAME IN POSITION TO PRESS SAID BODY ENGAGING SURFACE UPON SAID BODY AND THEREBY MOUNT THE THERMISTOR IN HEAT EXCHANGE RELATION WITH THE BODY, THROUGH SAID FACING LAYER. 